.header {
    position: fixed;
    top: 0;
    margin: 0 auto;
    width: 100%;
    height: 58px;
}
 .header .nav{
    width: 90%;
    height: 58px;
}
.header .nav .logo {
    width: 137px;
    height: 43px;
    margin: 10px 5px;
    background-size: auto 38px;
}
.header .nav ul li a{
    line-height: 58px;
}
/* 内容 */
.section{
    width: 750px;
    margin:0 auto;
}
.section .set .set1{
    width: 750px;
}
.section .set .set2{
    width: 750px;
    height: 453px;
}
.section .set .set2 img{
    display: block;
    margin-left: auto;
    margin-right: auto;
}
/* 底部 */
.footer{
    width: 100%;
    height: 100px;
}